Method and apparatus for strip feeding for sewing machines

ABSTRACT

In the feeding of a strip of material in sewing, variations in strip tension are reduced by the use of a feed roller, synchronized with the sewing mechanism of the sewing machine, followed by one or more tension devices, the lattermost tension device in the direction of strip travel being preferably in close proximity to the needle. When elastic strip is fed, gathering is accurately controlled irrespective of changes in supply roll inertia, and the building up of the proper degree of tension in the elastic strip is more rapid, resulting in simpler operation and reduced waste.

United States Patent [1 1 Zawick 1 METHOD AND APPARATUS FOR STRIP FEEDING FOR SEWING MACHINES [76] Inventor: George Zawick, 1706 Main St.,

Hellertown, Pa. 18055 [22] Filed: Nov. 8, 1973 [21] App]. No: 413,792

[52] US. Cl. 112/265; 112/113; l12/121.26; 112/152; 112/203 [51] Int. Cl. D05B 3/12 [58] Field of Search 112/2, 104, 105, 106, 113, 112/121.26, 121.27, 137, 203, 265,152, 158 R; 242/4701, 45, 47.08, 47.09

[4 1 Oct. 14, 1975 3,093,330 6/1963 Schmidt 242/45 3,847,099 1 1/1974 Braun 1 12/152 FOREIGN PATENTS OR APPLICATIONS 484,230 9/1953 Italy 112/158 R Primary Examiner-George H. Krizmanich Attorney, Agent, or FirmSmith, Harding, Earley & Follmer ABSTRACT In the feeding of a strip of material in sewing, variations in strip tension are reduced by the use of a feed roller, synchronized with the sewing mechanism of the sewing machine, followed by one or more tension devices, the lattermost tension device in the direction of strip travel being preferably in close proximity to the needle. When elastic strip is fed, gathering is accurately controlled irrespective of changes in supply roll inertia, and the building up of the proper degree of tension in the elastic strip is more rapid, resulting in simpler operation and reduced waste.

3 Claims, 5 Drawing Figures US. Patent Oct. 14, 1975 3,911,842

FIG. 4. so

FIG. 5.

FIG. 2. FIG. 3.

METHOD AND APPARATUS FOR STRIP FEEDING FOR SEWING MACHINES SUMMARY OF THE INVENTION This invention relates to sewing machinery and particularly to an apparatus for feeding strips of material from a supply to a sewing mechanism.

A clothing manufacturer very frequently has occasion to sew narrow strips of material to a garment. For example, strips of elastic tape are attached to the waistband portion of various types of garments, including underclothing, swimsuits, pantyhose and the like. Nonelastic tapes including ribbons, fabric tubing and the like are also frequently sewn to larger areas of garment fabric as trim. If an attempt is made to sew these strips of material to a garment using an ordinary sewing machine, irregular results may occur because of variations in the tension acting on the strip of material at the location of the sewing mechanism. These tension variations are not adequately remedied by an ordinary spring tension acting on the strip.

Tension variations may result from various causes. For example, where the strip material is fed from a supply roll, the change in the moment ofinertia of the supply roll as it is depleted causes a long-term variation in tension. Similarly, intermittent starting and stopping of the sewing mechanism can cause short-term variations in tension of a magnitude sufficient to cause objectionable results in the quality of the product. These irregularities in the product are of particular concern where elastic strips are to be sewn to a non-elastic fabric. In the sewing of elastic strips, control of tension is especially important because the tension on the strip determines the degree of gathering" of fabric which will occur when tension is relieved after the fabric and the elastic strip pass the feed dogs and presser foot of the sewing machine.

The foregoing problems in the sewing of strip material have been recognized and remedied in various ways by the use of special strip feeders. A typical strip feeder comprises a pair of rollers which cooperate to retard the strip material as it approaches the sewing mechanism. Control and adjustment of the speed of the rollers is necessary but difficult. Furthermore, the roller system, while suitable for elastic tapes, is not generally suitable for the feeding of non-elastic strips.

The roller mechanism is also necessarily rather bulky, and it is generally necessary to position the mechanism a considerable distance away from the point at which stitches are formed. When sewing begins, the tension on the strip follows an exponential function of time and approaches its ultimate value asymptotically. With a greater distance between the rollers and the sewing mechanism, a longer time is required for the necessary tension to build up. Consequently, when the rollers and the sewing mechanism are widely separated, time and material are wasted in operating the sewing machine until the desired amount of tension is built up.

The general object of this invention is to provide a simple strip feeder which produces a high-quality product with a minimum of irregularity.

A further object is to reduce the waste of time and material in start-up of the sewing machine.

A still further object of the invention is to provide a strip feeder adapted to accommodate both elastic and non-elastic strips.

The foregoing and other objects of the invention are accomplished by a strip feeder which may be briefly described as follows.

The strip feeder in accordance with the invention comprises a roller which is located in the path of the strip of material from a storage roll to the sewing mechanism of the sewing machine. The roller is preferably substantially cylindrical in shape and the surface of the roller which comes into contact with the strip is preferably composed of wood. The roller is rotated, at least during the operation of the sewing mechanism, at a speed such that, when the strip is wound about the roller, a pull exerted by the sewing mechanism on the length of the strip between the roller and the sewing mechanism causes the strip to be fed by -the roller toward the sewing mechanism at a rate which, if sustained, would be greater than the demand of the sewing mechanism. In other words, the peripheral speed of the roller exceeds the rate at which material is demanded by the sewing mechanism of the sewing machine.

The strip of material is preferably wound about the roller through at least one complete turn, and may be wound several times around the roller. In accordance with a preferred form of the invention, separators are provided for preventing parts of the winding of the strip about the roller from interfering with one another. For each separator, the roller is preferably provided with a circular groove coaxial with its axis of rotation and into which the separator extends. This arrangement insures against binding of the strip against itself or against the separating means. In an alternative form of strip feeder, separations are supported by a bar positioned in close proximity to the roller.

In operation, whenever a pull is exerted on the strip by the feed dog of the sewing mechanism, the strip is tightened about the roller, and increased friction between the roller and the strip causes the strip to be fed toward the sewing mechanism. The roller is preferably synchronized with the operation of the sewing mechanism by the use of a wheel, connected in driving relationship to the roller and bearing against the sewing machine drive wheel in driving relationship. This driving relationship is desirably accomplished by providing supporting means for the roller and the wheel connected to it, the supporting means being pivoted for swinging movement of the wheel to and away from the drive wheel with a spring urging the support in a direction such that the wheels are held against each other in driving relationship.

In accordance with the invention, the desired amount of tension on the strip at the location of the sewing mechanism, 'where the formation of stitches takes place, may be controlled by a relatively simple tension means such as a spring tension arranged to act on the length of the strip between the roller and the sewing mechanism. A relatively unobtrusive tension means being usable, it may be placed in close proximity to the sewing mechanism without obstruction to the operators vision or otherwise interfering with the sewing machines operation. When the tension means is located less than approximately 2 inches from the location at which sewing takes place, the distance being measured along the path of strip travel, waste of time and material in start up is greatly reduced, and in most instances, a high-quality product can. be produced with no preliminary operation of the sewing machine to build up tension.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view ofa sewing machine provided with feeding means in accordance with the invention;

FIG. 2 is an elevation of feeding mechanism in accordance with the invention as viewed from the side of the sewing machine opposite the operators position;

FIG. 3 is an elevation of the feeding mechanism as viewed from the left-hand side of FIG. 2;

FIG. 4 is a detailed elevation of one of the separators shown in FIGS. 1, 2 and 3; and

FIG. 5 is an elevation of an alternative feeding mechanism.

DETAILED DESCRIPTION Strips of material are sewn to larger pieces of fabric in a number of different ways, but preferably by means of an overlock stitch machine. A typical overlock stitch machine is indicated generally at 2 in FIG. 1. The sewing mechanism, which term as used herein refers to the stitch-forming and feeding elements at the location at which stitches are formed, comprises a presser foot 4, a reciprocating needle bar 6 and a feed dog and loopers (not illustrated).

The supply of elastic tape may take various forms, for example, the tape may be fed to the sewing mechanism from a roll or from a carton. A typical tape supply roll is shown at 8, mounted rotatably on mounting bracket 10. The tape 12 is fed to the sewing mechanism by a strip feeder generally indicated at 14, through a spring tension 16, guide 18, a second spring tension and guide plate 22. Spring tension 20 is positioned less than approximately two inches from the needle. It is the tension of the length of the strip between spring tension 20 and the sewing mechanism which must be carefully controlled in order to produce a high-quality product with a minimum of irregularity.

Strip feeder 14 is shown in detail in FIGS. 2 and 3. A stationary, elongated, U-shaped bracket 24 is provided, having uprights 26 and 28. A rod extends between uprights 26 and 28 and is secured in position by transverse pins. A support 32, which is preferably formed from a unitary twisted metal strip is pivoted on rod 30 at pivot points 34 and 36. The support carries a substantially cylindrical wooden roller 38, which is rotatably supported in bearings which are secured to vertical elements of the support. Wood has been found to produce a very smooth feeding and is an ideal material for roller 38. However, other materials, such as plastic may be used. A typical bearing is indicated in FIG. 3 at 40. A wheel 42 is secured to roller 38 for rotation therewith (although gearing may be provided if desired). The periphery of roller 42 is preferably formed of rubber or like material to provide for frictional engagement with the main drive wheel of the sewing machine. Returning to FIG. 1, wheel 42 is shown in contact and driving relationship with main drive wheel 44. Spring 46 (FIG. 2) urges support 32 in a direction such that wheel 42 is urged against drive wheel 44. With this preferred arrangement, roller 38 is synchronized with the sewing mechanism, rotating when the sewing mechanism is in operation, and remaining stationary when the sewingmechanism is not being operated. Furthermore, as the speed of the sewing mechanism increases, the speed of rotation of roller 38 increases.

' Roller 38 is' prov i ded with slots 48 in its periphery, the slots being circula'r and coaxial with the axis of rotation of the roller. These slots receive separators 50 which are held in slots 52 in support 32, and extend into slots 48 in the roller. A separator 50 is shown in detail in FIG. 4. It consists of a narrow piece of sheet metal having a hook 54 at its upper end for engagement with the corresponding slot 52 in support 32. The separators extend into thecorresponding slots 48 in roller 38 and prevent parts of the strip wound about roller 38 from interfering with other parts of the strip. Since the separators extend into slots in the roller, the strip is also prevented from binding between the separators and the roller.

When a demand by the sewing mechanism causes the strip material to become wound more tightly about roller 38, the rotation of roller 38 causes a small quantity of strip material to be fed from the supply roll toward the sewing mechanism. The operation is intermittent, the feeding of strip material stopping when the windings loosen about rotating roller 38. The strip feeder in accordance with this invention provides extremely smooth operation, feeding strip material as demanded by the sewing machine with almost no'tension on the length of strip extending between the feeder roll 38 and the spring tension 16. Consequently, the tension on the length of strip material between spring tension 20 and the sewing mechanism is influenced solely by the settings of spring tensions l6 and 20 with no substantial influence by the inertia of supply roll 8.

While a pair of spring tensions l6 and 20 are shown in FIG. 1, a single springtension at the approximate location of spring tension 20 will suffice for most purposes. In the event that a single spring tension is so used, it along influences the tension of the length of strip material between itself and the sewing mechanism.

An alternative form of strip feeder is shown in FIG. 5, comprising a roller 56 mounted in bearings on supports 58 and 60, these supports corresponding to the vertical elements of support 32 shown in FIG. 2. Roller 56, unlike the roller in FIG. 2, is not slotted. A bar 62 is secured between supports 58 and 60 and positioned in close proximity to the surface of roller 56 so as to provide a running clearance for the rotation of the roller. Separators 64 are secured to the bar and spaced from each other in a manner similar to separators 50 in FIG. 2. The strip material is wound around the roller and around separator support bar 62 on the outside. The separators 64 keep the adjacent turns of the strip from interfering with each other. While the turns of the strip are not in contact with the roller throughout its entire circumference because of the presence of the separator support bar, the frictional engagement between the strip and those parts of the roller with which it does come into contact is sufficient to feed the strip smoothly on demand in the same manner as accomplished by the strip feeder shown in FIG. 2.

Either of the alternative forms of strip feeder herein disclosed may be modified by elongation and by the provision of additional separators so that multiple strips may be fed by the same roller. When this is done, the

It will be apparent that numerous modifications may be made to the specific apparatus herein disclosed without departing from the scope of the invention as defined in the following claims.

I claim:

1. A sewing machine comprising: means for tempo rarily storing a strip of material, a sewing mechanism, and means for feeding a strip of material from the storing means to the sewing mechanism with a reduced time-variation in the tension of the strip at a location immediately preceding the sewing mechanism, the feeding means comprising a roller located in the path of feed of the strip of material from the storing means to the sewing mechanism and adapted to have the strip wound about it. and means for rotating said roller, at least during the operation of the sewing mechanism, at a peripheral speed greater than the demand of the sewing mechanism, the surface of said roller being provided with at least one circular groove coaxial with the axis of rotation of the roller, and stationary separating means extending into said groove. for preventing a part of the winding of said strip about said roller on one side of the separating means from interfering with a part of the winding on the other side of the separating means.

2. A sewing machine comprising: means for temporarily storing a strip of material, a sewing mechanism, and means for feeding a strip of material from the storing means to the sewing mechanism with a reduced time-variation in the tension of the strip at a location immediately preceding the sewing mechanism. the

feeding means comprising a roller located in the path of feed of the strip of material from the storing means to the sewing mechanism and adapted to have the strip wound about it, and means for rotating said roller, at least during the operation of the sewing mechanism, at a peripheral speed greater than the demand of the sewing mechanism, said sewing machine including tension means arranged to act on the length of the strip between the roller and the sewing mechanism at a location less than approximately two inches from the location at which sewing takes place.

3. The method of sewing a strip of elastic material to a piece of fabric or the like using a sewing machine comprising effecting rotation of a roller at a peripheral speed which exceeds the rate at which material is demanded by the sewing mechanism of the sewing machine, orienting said strip of fabric so that it extends from a supply, and around said roller, to the sewing mechanism, and, during the operation of said sewing mechanism wherein the formation of stitches is effected, effecting a pull on said strip of material such that it comes at least momentarily into frictional engagement with the periphery of the roller and is fed thereby toward the sewing mechanism and wherein tension is applied to the elastic strip between the sewing mechanism and a point preceding said sewing mechanism by a distance of less than two inches in the direction of strip travel. 

1. A sewing machine comprising: means for temporarily storing a strip of material, a sewing mechanism, and means for feeding a strip of material from the storing means to the sewing mechanism with a reduced time-variation in the tension of the strip at a location immediately preceding the sewing mechanism, the feeding means comprising a roller located in the path of feed of the strip of material from the storing means to the sewing mechanism and adapted to have the strip wound about it, and means for rotating said roller, at least during the operation of the sewing mechanism, at a peripheral speed greater than the demand of the sewing mechanism, the surface of said roller being provided with at least one circular groove coaxial with the axis of rotation of the roller, and stationary separating means extending into said groove, for preventing a part of the winding of said strip about said roller on one side of the separating means from interfering with a part of the winding on the other side of the separating means.
 2. A sewing machine comprising: means for temporarily storing a strip of material, a sewing mechanism, and means for feeding a strip of material from the storing means to the sewing mechanism with a reduced time-variation in the tension of the strip at a location immediately preceding the sewing mechanism, the feeding means comprising a roller located in the path of feed of the strip of material from the storing means to the sewing mechanism and adapted to have the strip wound about it, and means for rotating said roller, at least during the operation of the sewing mechanism, at a peripheral speed greater than the demand of the sewing mechanism, said sewing machine including tension means arranged to act on the length of the strip between the roller and the sewing mechanism at a location less than approximately two inches from the location at which sewing takes place.
 3. The method of sewing a strip of elastic material to a piece of fabric or the like using a sewing machine comprising effecting rotation of a roller at a peripheral speed which exceeds the rate at which material is demanded by the sewing mechanism of the sewing machine, orienting said strip of fabric so that it extends from a supply, and around said roller, to the sewing mechanism, and, during the operation of said sewing mechanism wherein the formation of stitches is effected, effecting a pull on said strip of material such that it comes at least momentarily into frictional engagement with the periphery of the roller and is fed thereby toward the sewing mechanism and wherein tension is applied to the elastic strip between the sewing mechanism and a point preceding said sewing mechanism by a distance of less than two inches in the direction of strip travel. 